Root starch process



July

R. H. SCHILLING ET AL 2,380,374

ROOT STABCH PROCESS Filed April 20, 1942 Y INVENTORS RICHARD H. SCHl-LLING GEORGE J. MITCHELL BY ATTY.

Patented July 31,

7 poor s'rsacn mocsss Richard H. Schilling and George J. Mitchell,

Minneapolis, Mirna, assignors to General Mills,

Inc., a corporation oi Delaware Application April 20, 1942, Serial No. 439,664

Claims.. (Cl. 127-66) The present invention relates to'a process of separating starch from roots. More particularly, it relates to a process of separating starch from roots which makes possiblemuch greater recovery of the starch and at the same time makes possible the preparation of a pure product.

While the process is described hereinafter in detail with respect to mandioca, it will be apparent that other root starches may be treated according to the present invention without departing from the spirit thereof. 1

At present starch is prepared from mandioca roots by wet grinding oi thefresh roots. It has been important that the roots be processed on the same day that. they are removed from the ground for otherwise the enzymes apparently convert the starch into an unsatisfactory form. In a modification of this process the roots are broken up into relatively large pieces which may then be dried. Subsequently these dried pieces are soaked in water for a considerable period of time and are then wet ground and the starch removed from them. These processes have not been wholly satisfactory as yields have been small, in many instances considerably less than 50 per cent, and the product has been very im ure. The present applicants have found that mandioca roots may be dried for storage purposes after which the! may be processed according to the present invention to produce an improved product and to provide a materially increased yield. Preferably the roots are sliced intosmall pieces which are then washed and dried. as in the manner referred to above. These dried pieces are conventionally re-' ferredtoasraspas. Inthiswayitispossibleto prepare a material which can be stored for considerable priods of time and may beshipped to a central processing plant. Thus as the materials are collected they may be processed in large plants making possible more accurate control of the process and more efllcient manipulation. The dried roots or raspas may then be dry ground in any suitable typeof mill, for example a hammer mill, after which they are mixed with water, and the starch is removed by washing. It has been found that this procedure makes possible a substantially increased yield of a very pure product.

The following specific description of the invention in connection with the diagrammatic illustration in the drawing is for the purpose of illustration only and is not to be construed as limiting the invention thereto.

The ra-spas from storage are advanced along conveyor is which discharges into hopper I I provided with a suitable screw discharge means at the bottom thereof. From this feeding means the raspas are fed into the mill H which preferably is a hammer mill and are discharged therefrom by means of a blower. The ground material is separated in cyclone separator l3 and is discharged into the mixing device II This mixing device is provided with an agitator 15 which may be of any form suitable for mixing a dry ground material with water, although we prefer a form that will progressively advance the material from the inlet end to the discharge end, thus making possible a. continuous operation. Water is introduced from source It. It appears that the working of the comminuted material and water in the form of a dough tends to separate the starch particles from the fibers so that a better separation may be effected in the extracting steps. The ground material and the water, in the form of a dough, are discharged from the mixer it into a. series of extractors i'l into which a considerable quantity of additional water is introduced. These extractors are provided with agitating means which serve to make a slurry out of the mixture of dough and water. The agitators in these extractors are likewise preferably of the type which advance the material continuously therethrough. The material discharged from the end of the extractorsis in the form of a slurry which is then passen over screen it for the purpose of remov- For the purpose of illustration we have found that a 12X! silk screen is suitable for this purpose. The slurry passing through the screen is introduced into a centrifuge is. This centrigue is preferably of the continuous type into which material tobe separated can be continuously fed and the twoseparated materials may be continuously discharged. An example of such a centriiuge will be found in United States Patent No. 1,923,455. The heavy eflluent is in the form of a concentrated slurry which may be run through a suitable filter 20 which may be continuous. Th'e.

filtered starch discharged from filter 20 is then run through a suitable drier 2| and discharged from the opposite end thereof. The dried starch may then be advanced on conveyor 22 and discharged into mill 23 where it is reduced to a suitable size. The ground starch is separated in cyclone separator 24 from which it may be run to storage or otherwise suitably disposed of. The light eiiiuent from centrifuge l9 which contains most of the pulp and fiber and a small amount of starch may be suitabhr disposed to waste or may be recovered for feed purposes. The overs on screen it are run to an additional set of extractors 'Iheoversonscreen Thesta'rchpassing large particles on screen II. 28 may be sent to waste.

through screen 20 may be returned to the extracm n together with the nit ate 'irom filter a. to be used in a subsequent extraction. It will be apparent that as" the concentration of impurities in the recycled material increases, it may be necessary to discard part and recycle re"- mainder. g

It is preferred to maintain the starch slurry at apHbetween5 and'lasitisfoundthatatthi value sep ration is facilitated and yields and purj ity are improved. The quantity of water employed in the process is relatively unimportant but a slurry contalning'between 5 and 10 per cent.

solids at the point of introduction to the centriiuge h8-s proven highly satisfactory.

It will'be apparent from the above description that the present invention and eflicient production .of starch from roots. The amount of equipment required is small in comparison with the process heretofore used Furthermore, the time period required for processing has been reduced to a small fraction of that necessary in conventional processes.

While the invention ha been describedfin detail! it is to be understood that various modiilca-' tions thereof may be made without departing from the scope of the claims appended hereto.

We claim as our invention:

1; Process of recovering starch from roots which comprises, comminuting driedroots, mixing the comminuted'roots with water to form a makes possible a'rapid 2 m ses it into which water may be introduced from any z-rm of recovering starch i'roin mandioca. available source. In this extraction additional which comprises comminuting raspas in'a dry starch is extracted and may be separated from the condition, mixing the comminuted raspas with water to form a loosen starch from the fibrous the dough with water to form a starch slurry. concentrating said slurry by centrifugal means, filtering the concentrated slurry and drying the resultant starch. v

"mg 3. Proces of recovering starch from mandioca which comprises, comminuting raspas in a dry condition. mixing the comminuted mm with water to form a dough, mixing the dumb with water to form a slurry. separating relatively large particles from the slurry, concentrating the sl by centrifugal means. filtering the concentra starch. mixing water slurry, drying the resultant with the'large particles separated from the slurry, separating large particles from the resultant mixture and returning the water and lines for mixing with the dough.

4. Process of recovering starch from rootswhich comprises comminuting dried roots, mixdough. working the dough to loosen starch from the fibrous material, mixing the dough with water to forms thin starch slurry,'concentrating said slurry by centrifugal means, slurry anddrying theresultant starc Patent No. 2, 803%.

It is thereby certified the above numbered patent re and column;

CERTIFICATE OF CORRECTION.

RICHARD H. SCHILLlNG, 'ETQAL.

' ing the comminuted roots with water to form a dough, working the dough to loosen starch from the fibrous material, mixing the dough with water to convert it to a slurry, recovering starch from said slurry, and returning an impure starch slurry to the step of thedough with water to tional 5. Process of, recovering from roots which comprises ing the comminuted .comminuting dried roots, mixroots with water toform a as dough, working the dough to loosen starch from the 'flbrous'material, mixing the dough with wsteito form a starch slurry, and recovering the starch memo a. some. oaoaos: c.

July 31 19145.

that error appeare in th printed specification quiring correction-as follows: Page 1, secline 50, for "passen. over screen 18 for'the purpose 1 of, remov-"e read ,--passed over screen 18' for thepurpose of removing any large' par ticls: lflbt suitably :ceriuciei:l

of the case in the Patent Office.

and that the said Letters Pat nt should beread with this correction therein that the Signed and sealed this 20th dayof November, A. D. 1914.5.

(Seal) First Assistant Commissioner of Leslie Frazer Pa tents dough, working the dough to convert it to a slurry i'or the recovery'of addir 'Iheoversonscreen Thesta'rchpassing large particles on screen II. 28 may be sent to waste.

through screen 20 may be returned to the extracm n together with the nit ate 'irom filter a. to be used in a subsequent extraction. It will be apparent that as" the concentration of impurities in the recycled material increases, it may be necessary to discard part and recycle re"- mainder. g

It is preferred to maintain the starch slurry at apHbetween5 and'lasitisfoundthatatthi value sep ration is facilitated and yields and purj ity are improved. The quantity of water employed in the process is relatively unimportant but a slurry contalning'between 5 and 10 per cent.

solids at the point of introduction to the centriiuge h8-s proven highly satisfactory.

It will'be apparent from the above description that the present invention and eflicient production .of starch from roots. The amount of equipment required is small in comparison with the process heretofore used Furthermore, the time period required for processing has been reduced to a small fraction of that necessary in conventional processes.

While the invention ha been describedfin detail! it is to be understood that various modiilca-' tions thereof may be made without departing from the scope of the claims appended hereto.

We claim as our invention:

1; Process of recovering starch from roots which comprises, comminuting driedroots, mixing the comminuted'roots with water to form a makes possible a'rapid 2 m ses it into which water may be introduced from any z-rm of recovering starch i'roin mandioca. available source. In this extraction additional which comprises comminuting raspas in'a dry starch is extracted and may be separated from the condition, mixing the comminuted raspas with water to form a loosen starch from the fibrous the dough with water to form a starch slurry. concentrating said slurry by centrifugal means, filtering the concentrated slurry and drying the resultant starch. v

"mg 3. Proces of recovering starch from mandioca which comprises, comminuting raspas in a dry condition. mixing the comminuted mm with water to form a dough, mixing the dumb with water to form a slurry. separating relatively large particles from the slurry, concentrating the sl by centrifugal means. filtering the concentra starch. mixing water slurry, drying the resultant with the'large particles separated from the slurry, separating large particles from the resultant mixture and returning the water and lines for mixing with the dough.

4. Process of recovering starch from rootswhich comprises comminuting dried roots, mixdough. working the dough to loosen starch from the fibrous material, mixing the dough with water to forms thin starch slurry,'concentrating said slurry by centrifugal means, slurry anddrying theresultant starc Patent No. 2, 803%.

It is thereby certified the above numbered patent re and column;

CERTIFICATE OF CORRECTION.

RICHARD H. SCHILLlNG, 'ETQAL.

' ing the comminuted roots with water to form a dough, working the dough to loosen starch from the fibrous material, mixing the dough with water to convert it to a slurry, recovering starch from said slurry, and returning an impure starch slurry to the step of thedough with water to tional 5. Process of, recovering from roots which comprises ing the comminuted .comminuting dried roots, mixroots with water toform a as dough, working the dough to loosen starch from the 'flbrous'material, mixing the dough with wsteito form a starch slurry, and recovering the starch memo a. some. oaoaos: c.

July 31 19145.

that error appeare in th printed specification quiring correction-as follows: Page 1, secline 50, for "passen. over screen 18 for'the purpose 1 of, remov-"e read ,--passed over screen 18' for thepurpose of removing any large' par ticls: lflbt suitably :ceriuciei:l

of the case in the Patent Office.

and that the said Letters Pat nt should beread with this correction therein that the Signed and sealed this 20th dayof November, A. D. 1914.5.

(Seal) First Assistant Commissioner of Leslie Frazer Pa tents dough, working the dough to convert it to a slurry i'or the recovery'of addir 

